Method of casting by catching free-falling molten metal mass

ABSTRACT

Manufacturing cutting tools from rapidly solidifying alloys in which the molten alloy mass is rapidly transferred between a pair of operating movable mold means which are provided with suitable recesses for forming said molten alloy mass into the desired shape. The pair of mold means are adapted to rapidly cool the molten alloy mass while it is being shaped.

United States Patent Esslinger et al.

[451 May 16,1972

METHOD OF CASTING BY CATCHING FREE-FALLING MOLTEN METAL MASS Inventors:Paul Esslinger, Frankfurt am Main; Rudolf Walkling, Frankfurt am Main-Bockenheim,

both of Germany Assignee: The Battelle Development Corporation,

Columbus, Ohio Filed: June 30, 1969 Appl. No.: 837,726

Foreign Application Priorlty Data July 3, 1968 Germany ..P 17 58 596.5

US. Cl ..l64/l13, 164/136, 65/123 Int. Cl. ..B22d 27/10, B22d 35/00Field ofSearch ..164/5l, 113, 120, 136, 155,

[56] References Cited UNITED STATES PATENTS 2,686,864 8/1964 Wroughtonet a]. ..l64/25l X 3,240,582 3/1966 Stutske ..65/ 123 X 3,435,880 4/1969Goetz et al 164/l55 Primary Examiner-R. Spencer Annear Attorney-ArthurO. Klein [57] ABSTRACT Manufacturing cutting tools from rapidlysolidifying alloys in which the molten alloy mass is rapidly transferredbetween a pair of operating movable mold means which are provided withsuitable recesses for forming said molten alloy mass into the desiredshape. The pair of mold means are adapted to rapidly cool the moltenalloy mass while it is being shaped.

4 Clalrns, 1 Drawing Figure III/IA Inventor P L ESJLING ER and l ludol}WALKLING H1 air afforne y METHOD OF CASTING BY CATCIIING FREE-FALLINGMOLTEN METAL MASS BACKGROUND OF THE INVENTION The cutting knives ofcutting and machining tools have generally the shape of plates. Theseplates are made of sintered hard metal alloys which have a very highability to maintain their cutting power and have generally also greatwear resistance. Such cutting tools are shaped as plates and have awelded layer of sintered hard metal alloys. It is also known tomanufacture such cutting tools by spraying a powder consisting of thealloyed metal which is then heated to a sintering temperature and isthen sintered. Due to spraying the alloyed metal in powder form it israpidly cooled after having been heated to the sintering temperaturewhich gives the eventually resulting cutting tool some very favorablecharacteristics; for example, a very fine and uniform dispersion of thecarbides.

Due to the latter the wear resistance and the mechanical characteristicsof the surface of the cutting knife are improved.

Thus the rapid cooling which results by manufacturing the cutting toolout of powdered particles consisting of the alloyed metal and sprayingsaid powdered particles so as to obtain the cutting tool constitutes animportant advantage in the manufacturing of such cutting tools. However,such a manufacturing technique is also accompanied with certaindisadvantages. For example, the costs of manufacturing such cuttingtools are relatively high. The advantages which follow a rapid coolingof an alloy melt are partially eliminated by the fact that the sinteringprocess utilized for manufacturing the cutting tools requires somerelatively high temperatures.

SUMMARY OF THE INVENTION It is accordingly a principal object of theinvention to manufacture a cutting tool without using a sinteringprocess.

It is a more specific object of this invention to provide an apparatusin a process for manufacturing cutting tools wherein a molten mass ofalloy metal is rapidly moved between a pair of mold means which areprovided with recesses for shaping the molten mass into a cutting tooland which are adapted to rapidly cool the molten mass of alloy metal.

DESCRIPTION OF DRAWING The invention is illustrated by way of example inthe accompanying drawing which forms part of this application and inwhich the sole FIGURE illustrates schematically in an elevational viewthe arrangement of this invention.

DESCRIPTION OF PREFERRED EMBODIMENT The example of the invention whichis illustrated in H6. 1 includes a crucible or pot 11 having a movablebottom 12. This movable bottom may, for example, be mounted on pistonrod 4 having a piston head 13 which is reciprocally mounted in a pistoncylinder 7. The crucible 1 contains an alloy mass 3 from which cuttingplates, knives, or tools can be fabricated. When the alloy mass 3 hasreached a sufficiently high temperature, so that it is in a moltenstate, the bottom 12 is quickly moved downwardly by means of thepiston-cylinder arrangement as will be set forth in detail hereinbelow.

The molten alloy is, for example, heated by means of an inductive coilwhich is connected to a not illustrated electric power source. The coil1 is mounted in a protective layer 2 of suitable material such as, forexample, asbestos.

It is important that the flat bottom 12 moves downwardly at a velocitywhich is somewhat slower than the free-fall velocity of the molten mass3 so that the latter remains as a closely formed compact mass which isnecessary for advantageously shaping the molten mass. The bottom 12 thusmoves the molten mass 3 between a pair of cooling members which consistof material having a high heat conductivity, such as for example, copperor silver. One cooling member 5' of the pair is substantially flat,whereas the other cooling member is shaped as illustrated in thedrawing. Once the molten mass 3 has reached the position between thecooling members 5 the descending velocity of the flat bottom 12increases, by virtue of the action of the piston-cylinder arrangement,so that the bottom 12 moves ahead of the descending mass 3. Thedescending velocity of the bottom 12 is such that the bottom 12 hasreached a position immediately below the lower peripheral region of thetransversely moving cooling members 5 when the descending molten mass 3has reached a substantially central position between the pair of coolingmembers 5. The pair of cooling members 5 are then rapidly moved togetherthereby catching the molten alloy mass 3 and subjecting it to anintensive cooling process, whereby the molten mass 3 is shaped into aflat cutting tool. The final shape of the cutting tool is defined by theconfiguration of the recess or recesses 11 in one of the cooling members5. Since this cooling member has the shape of a truncated cone theremoval of excess molten metal is assured.

The pair of cooling members 5 may also be so shaped that they both havea plurality of recesses 6. It is, of course, also possible to provideonly one cooling member 5 with one recess 11, whereas the other coolingmember is provided with a corresponding projection; so that when thepair of cooling members 5 have completely moved together they define afree space between themselves. This free space then detennines the finalshape of the cutting plate.

It is also possible to shape the pair of cooling members 5 in such a waythat one cooling member is provided with a plurality of recesses 6'whereas the other cooling member is provided with a plurality ofprojections, so that the pair of cooling members when taken together,form an arrangement similar to that of a waffle iron. With such anarrangement it is possible to produce a plurality of cutting plates inone cooling operatron.

The recesses and projections of the cooling members are so dimensionedthat they adapt themselves to the molten alloy mass as it shrinks duringthe cooling process while the pair of cooling members 5 are subjected toa continuous pressure, thereby providing a continuous cooling of thealloy mass.

The complicated movement of the flat bottom 12 is effected pneumaticallyas follows:

The bottom 12 is connected to a piston rod 4 which terminates in apiston head 13. The latter is slidably reciprocally movably mounted in acylinder 7 and divides the latter in two chambers 9 and 10 the volumesof which vary as the piston head 13 moves in the cylinder 7. The pipes14, 14 are respectively connected to the chambers 9 and 10, on the onehand, and to a not illustrated pneumatic power source, on the otherhand. The pipes 14, 14 are provided with adjustable air flow regulatingvalves 8. By adjusting the valves 8 according to a predetermined schemethe pressures in the chambers 9 and 10 vary in such a way that thebottom plate 12 moves in the aforedescribed manner.

In the illustrated embodiment the cooling members 5 are actuated bymeans of a pair of solenoids 6. The solenoids 6 are provided withnon-illustrated pneumatic switches which actuate the solenoids at apredetermined point in time in the operative cycle of the arrangement.This point in time is determined by the fact that cooling members 5 canonly move together after the bottom plate 12 has descended below thelower peripheries of the cooling members.

The alloy metal mass 3 can also be molten in alternate ways. Forexample, the mass 3 can be heated in a tube, consisting of graphite orother ceramic material, the bottom of which forms the support surfacefor the mass 3. The tube can be heated by means of an induction coil oran electric resistance wire arrangement. Thus the mass can be heated toits melting temperature in many different ways. What is important isthat the molten mass retains a compact form while descending between thepair of cooling members 5. lt is particularly important to avoid that athin or thick thread of molten metal flows downwardly between the pairof cooling members. It is also important to move the molten mass 3 asquickly as possible between the cooling members 5.

have been found to be suitable:

Percent 0.8 C 4.6 Cr... 6W.. Mo 5V Remainder iron. 1.2 4.5 Cr. 11 w..5M0. 3V 1 Co. 0.

1.5 4.2 Cr... 6.15 w 5 Mo 3.2V, 4 800. Do.

1.6 4.6 Cr... 12.5 w-.- 1 Mo 4v D0. Stelllte... 2.6 0.... 31 On... 31 Cr17w Do.

Furthermore, alloys having ingredients based on the aforementionedcompositions with a high content of carbon and/or vanadium are alsosuitable for the manufacture of cutting plates in accordance with theprocess of this invention.

The last mentioned compositions, if subjected to the conventionallyknown processes, exhibit a correspondingly high wear resistance andtherewith a high ability to retain or maintain their cutting powerbecause the compositions themselves are quite brittle. Such compositionsare particularly suitable for the process of this invention because, asa result of the rapid cooling and solidification, the molten masssolidifies in a refined state thereby eliminating the globules presentin the molten mass and resulting in a better distribution of thecarbides. The process of this invention is therefore capable ofproducing a cutting plate having a higher toughness which can onlynormally be obtained with metal alloys having a substantially lowercarbide content.

The cutting plates manufactured in accordance with this invention can bemounted by conventional means onto a shaft or a tool consisting of acheap material such as for example by means of threading the cuttingplate onto the shaft or welding it onto the shaft.

in order to obtain the afore-recited advantageous characteristics thecutting plates manufactured in accordance with this invention must besubjected to a cooling of at least l0 C./sec. This cooling rate can beobtained by means of the apparatus discussed herein without anydifficulty.

Although the invention is illustrated and described with reference toone preferred embodiment thereof, it is to be expressly understood thatit is in no way limited to the disclosure of such a preferredembodiment, but is capable of numerous modifications within the scope ofthe appended claims.

We claim:

1. A process for manufacturing cutting tools and the like out of quicklysolidifying alloys, comprising the steps of supporting a metal alloy ata first level on a supporting means while heating a metal alloy so thatit forms a molten mass on said first level;

descending said molten mass by said supporting means at a first velocityless than the free fall velocity of said molten mass to a second levelbetween a pair of operatively movable cooling members;

said supporting means descending at a velocity larger than the free fallvelocity of said molten mass after the latter has reached said secondlevel; catching said molten mass at said second level by means of saidmovable cooling members which quickly cool and shape said molten mass.

2. The process as set forth in claim 1, wherein said pair of coolingmembers are shaped as a pair of opposite plates, at least one plate ofthe pair of plates having recess means for shaping the cutting toolwhile subjecting it to cooling.

3. The process as set forth in claim 2, wherein said metal alloyconsists of 0.8 percent to 2.5 percent C, 4.5 percent to 31 percent Cr,6 percent to 17 percent W, 1 percent to 5 percent Mo, 3 percent to 5percent V, 4.8 percent to 43 percent Co and the balance iron.

4. The process as set forth in claim 2, wherein said cutting tool isshaped as a plate having the following maximum dimensions: 20 X 20 X 5mm".

Dedication 3,662,811. Paul Essli'nger, Frankfurt am Main, and RudolfWalkling, Frankfurt am Main-Boekenheim, Germany. METHOD OF CASTING BYCATCI-IING FREE-FALLING MOLTEN METAL MASS. Patent dated May '16, 1972.Dedication filed Aug. 2, 1974, by the assignee, The Battelle DevelopmentGorpomtz'on.

'Hereby dedicates to the People of the United States the entireremaining term of said patent.

[Ofiiaz'alGaeette N ovember 12, 1974.]

2. The process as set forth in claim 1, wherein said pair of coolingmembers are shaped as a pair of opposite plates, at least one plate ofthe pair of plates having recess means for shaping the cutting toolwhile subjecting it to cooling.
 3. The process as set forth in claim 2,wherein said metal alloy consists of 0.8 percent to 2.5 percent C, 4.5percent to 31 percent Cr, 6 percent to 17 percent W, 1 percent to 5percent Mo, 3 percent to 5 percent V, 4.8 percent to 43 percent Co andthe balance iron.
 4. The process as set forth in claim 2, wherein saidcutting tool is shaped as a plate having the following maximumdimensions: 20 X 20 X 5 mm3.